Input Devices And Their Use

ABSTRACT

A touch-sensitive input device has an exposed, continuous surface defining a planar area, and a grid of sense elements coextensive with the area of the exposed surface and responsive to engagement of the exposed surface by an operator to establish a position of said engagement of the exposed surface. The exposed surface varies in elevation across its planar area to form a series of tactile features. The exposed, continuous surface is affixed to the grid of sense elements. An electronic circuit is configured to interpret large-scale capacitance variations of the grid as an intended input small-scale capacitance variations of the grid as a position of engagement of the exposed surface by the operator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority from U.S. provisional patentapplications 60/205,910, filed May 22, 2000; 60/234,959, filed Sep. 23,2000; and 60/259,983, filed Jan. 8, 2001, the entire disclosures ofwhich are incorporated herein by reference.

TECHNICAL FIELD

This invention relates generally to devices, such as touchpads, keypadsand voice recognition systems, for inputting data into electronicdevices, and more particularly to keypads in which output keystrokes aredetermined both from individual switch activation and from the combinedactivation of adjacent switches.

BACKGROUND

The miniaturization of electronic products is one of the primary tenetsof technologic advance. Competitive advantage and the success of aproduct line largely hinges on the ability of a company to successfullyprovide products that are both increasingly functional and increasinglyportable. As technology advances, it becomes increasingly possible tominiaturize electronic circuitry below human scale, with the resultbeing that the interface (e.g., screens, keypads, cursor controldevices) can come to limit the size of portable products. Therefore, asportable products enter this realm, the ergonomic quality and size oftheir input devices (such as keypads) will have a growing significanceto product acceptance and success. Of special significance is thetelephone keypad, because it has such importance worldwide as afundamental communication and economic tool. International standardshave been established, for example, for the minimum dimension betweenadjacent key switches to accommodate typical human fingertips. By “key”I mean an element, of an array of elements over a surface, which whenstruck produces an identifying output corresponding to the location ofthe element. The term “key region” includes, for example, a localizedregion having key-like behavior on a touch-screen and a localized regionof a keypad formed by placing a membrane over an array of contactswitches. A “keypad” is an array of keys or key regions and includes,among other things, a conventional keypad (such as is found on mosttelephones, calculators and such), a keyboard, and similartouch-sensitive arrangements implemented with a touch-screen or withdemarcated zones on a membrane surface. While such a surface is commonlyplanar, it may also be curved.

Some of my earlier work has been directed at reducing the size ofkeypads through the development of keypads in which output keystrokesare determined both from individual switch activation and from thecombined activation of adjacent switches. Some of my earlier work isdisclosed in my U.S. Pat. Nos. 5,612,690 and 5,973,621, the entirecontents of which are incorporated herein by reference. I refer to suchkeypads herein as “IACK” keypads, or Independent-And-Combination-Keykeypads.

In this context, “independent keys” or “independent key regions” areelevated regions of a keypad surface with individual graphical elements,which provide a corresponding output when individually pressed. A“combination key” or “combination key region,” on the other hand, is alocally depressed region of an IACK keypad surface that provides aunique output as a consequence of the simultaneous or near-simultaneousmanipulation of a set of two or more adjacent (e.g., diagonally adjacentor “kitty-corner”), independent key regions, typically corresponding toa central graphical element. I use the term “defined combination” torefer to any combination of independent keys that corresponds to acombination key, as interpreted by an associated device. Conversely, an“undefined combination” is a set of independent keys that do not, whensimultaneously depressed, correspond to a defined combination key.

Thus, an IACK keypad is a keypad that includes both independent andcombination keys or key regions. Such keypads typically have independentkey regions identified by graphical elements on surfaces slightlyelevated above adjacent surfaces carrying other graphical elements thatidentify combination key regions, for example. It is possible to designsuch keypads with advantageously very small spacing between adjacentindependent key regions.

It is desirable to increase the accuracy of IACK keypads and other inputdevices with respect to the interpretation of the intent of the user,regardless of the switch technology used. There is a special need tobetter determine whether the user intends an individual or a combinationkey output in an IACK keypad, in those implementations when a strongtactile feedback is desired, such as is provided by metal snap domes.Improvements in the ergonomics of such keyboards are also desired, aswell as better algorithms to simplify the interpretation of input, suchas for use in telephones and such.

Additional improvements in the design and implementation of keypads andother input devices are desired.

SUMMARY

The present invention features improvements in the design of IACKkeypads and other data input means, and their integration intoelectronic devices.

According to one aspect of the invention, a telephone with an IACKkeypad defining both combination key regions and independent key regionsarranged in alternating columns has columns of combination key regionsthat include multiple numerical columns together including numericalregions corresponding to numerals 0 through 9, with each numericalcolumn containing a plurality of the numerical regions, and at least oneother column containing key regions corresponding to punctuationsymbols.

Preferably, the telephone has three numerical columns, such that thenumerical columns together form a standard telephone key layout, with aleft numerical column containing 1,4,7, a middle numerical columncontaining 2,5,8,0, and a right numerical column containing 3,6,9.

In some embodiments, the key regions are defined by correspondingsensible features on an exposed surface of a flexible membrane. By“sensible” I mean capable of being sensed by the human senses. Forexample, the sensible features may include changes in elevation acrossthe surface of the membrane (e.g., sensible by touch). In other casesthe sensible features may be simply visual distinctions. Preferably, thenumerical key regions are visibly larger than the key regionscorresponding to punctuation symbols.

In some preferred embodiments, the independent key regions and thecombination key regions are of different size.

The independent key regions together include, for some applications,regions corresponding to letters of an alphabet (such as the letters Athrough Z of the English alphabet, for example).

The independent key regions are preferably spaced apart with a spacingof no more than about one-half of a human fingertip width, forparticularly compact keypad layouts, and each key region carries anassociated, visible legend in some cases. The combination key regionsmay also be arranged in columns of alternating width

In some configurations, the numerical columns have a visibly differentcoloration than the one or more columns containing predominantlypunctuation symbols, and the columns may alternate in such coloration,as dark-light-dark, for example.

In a preferred embodiment, the independent key regions are arranged insix vertical columns, as determined by key legend orientation, with theindependent key regions arranged in first, third, fifth, seventh, ninthand eleventh vertical columns and containing regions corresponding toletters, the numerical combination key region columns forming second,sixth and tenth vertical columns, and fourth and eighth vertical columnsincluding key regions corresponding to punctuation symbols. Columnnumbering progresses from either lateral side of the keypad.

The telephone may be configured to register different punctuationsymbols as one of the key regions corresponding to punctuation symbolsis actuated twice in succession, preferably two or more related symbols.For example, pushing the colon key twice registers a semi-colon; pushingthe period key twice registers a comma, and so forth.

According to another aspect of the invention, an IACK keypad has a coverwith an exposed surface defining both combination key regions andindependent key regions arranged in alternating columns, with theindependent key regions comprising nubs elevated above the combinationkey regions. The exposed surface forms a continuous, smooth contourbetween adjacent independent key regions, void of delineations markingshared boundaries between adjacent independent key grid spaces of anunderlying key space grid. By “continuous, smooth contour” I mean thatthe surface between the nubs is void of tactile delineations markingshared independent key boundaries, such as edges of independentlymovable keys. Such a continuous, smooth contour can (and in some cases,preferably does) carry visible legends corresponding to the combinationkey regions associated with such smooth surfaces.

In some preferred embodiments, the nubs are diamond-shaped, with ends orpoints directed between adjacent combination key regions.

According to another aspect of the invention, an IACK keypad definesboth combination key regions and independent key regions arranged inalternating columns and having a standard orientation defined by legendsassociated with the independent and combination key regions, with thealternating columns disposed along lines canted at an angle (e.g., anangle of 45 degrees) with respect to the standard orientation of thekeypad.

According to another aspect of the invention, a telephone has a keypadincluding key regions arranged in columns including two numericalcolumns, a majority of key regions in the numerical columnscorresponding to selected numerals from the list consisting of 0 through9, and at least one punctuation column, a majority of key regions in thepunctuation column corresponding to punctuation symbols.

According to yet another aspect of the invention, an IACK keypad has acover with an exposed surface defining both combination key regions andindependent key regions arranged in alternating, staggered columns andalternating, staggered rows. The exposed surface forms a continuous,smooth contour between adjacent independent key regions, void of visiblefeatures marking a boundary, parallel to a column or row, betweenadjacent key regions.

According to another aspect of the invention, a keypad has an array offirst and second sets of keys. The first set of keys is arranged in afirst plurality of rows, each row having a second plurality of members,each member being a key having a contact region of a first shape and afirst area, the first shape and first area corresponding at leastroughly to dimensions at the tip of a human finger. The first set ofkeys also defines a set of interstitial regions that are unoccupied bymembers of the first set, while members of the second set of keys arelocated in the interstitial regions and have a second shape and a secondarea (of, e.g., a diamond shape), the second area being substantiallysmaller than the first area.

In some preferred embodiments, the contact region of each key in thefirst set lies in a first horizontal plane and the contact region ofeach key in the second set lies in a second horizontal plane that isdisposed above the first horizontal plane.

In some applications the keypad is an IACK keypad, in which each memberin the first set of keys is a combination key and each member of thesecond set of keys is an independent key.

In some embodiments the keypad also includes a non-linear tactilefeedback system coupled to the array of keys to provide tactile feedbackfor each key approximately proportional to the area of the contactregion of such key.

According to another aspect of the invention, an IACK keypad has a coverwith an exposed surface defining both combination key regions andindependent key regions arranged in alternating, staggered columns andalternating, staggered rows of a key matrix, and tactile nubs positionedjust outside the key matrix, between fourth and fifth rows ofcombination key regions, to demark an edge of a telephone keypadconsisting of combination key regions of first through fourth rows ofthe matrix.

In accordance with one aspect of the invention, the “interstitial”nature of combination keys is withheld from the user by eliminating thevisible grid connecting independent keys as shown in prior art IACKkeypads. Unlike prior art IACK keypads in which the combination keys areimplemented as elements disposed at the intersection at the edges ofindependent keys, this invention implements independent keys as theinterstitial areas of (much larger) combination keys. In accordance withanother aspect of the invention, a high degree of tertiary functionality(such as punctuation) is provided in a telephone layout of an IACKkeypad by alternating columns between classes of characters, such asnumbers, punctuation, numbers, punctuation, numbers. This aspect may befurther improved by alternating the width and/or coloration of adjacentrows. In accordance with one aspect of the invention, the IACK keypadstructure is rotated 45 degrees, thereby creating a reduced width IACKkeypad. This structure enables a standard “QWERTY” layout to provide ahigh standard of ergonomic comfort in a narrow width (of as little as 58millimeters, for example).

According to another aspect of the invention, a touch-sensitive inputdevice (such as a keypad or touchpad, for example) has an exposed,continuous surface defining a planar area, and a grid of sense elementscoextensive with the area of the exposed surface and responsive toengagement of the exposed surface by an operator to establish a positionof said engagement on the exposed surface. The exposed surface varies inelevation across its planar area to form a series of tactile features.

In some embodiments, the tactile features comprise elevated nubs.Preferably, the elevated nubs extend at least about 0.75 millimeter fromadjacent regions of the exposed surface. In some instances, the exposedsurface of the device carries legends associated with said tactilefeatures. The tactile features may define distinct regions of thesurface corresponding with associated alphanumeric characters, for someapplications.

In some cases, the input device is configured to output a sequence ofalphanumeric characters as corresponding tactile features of the surfaceare engaged sequentially, such as with a keypad. In some preferredembodiments, the device is an IACK keypad, with the tactile featurescomprising nubs defining independent key regions of the IACK keypad.Preferred embodiments also include an electronic circuit adapted totemporarily display alphanumeric characters on a screen as an operatortraverses the exposed surface, the displayed alphanumeric charactersbeing selected to correspond to a position of engagement of the exposedsurface by the operator.

According to another aspect of the invention, an electronic devicecomprises an IACK keypad having an exposed, continuous surface definingboth independent key regions and combination key regions, a grid ofsense elements underlying the surface of the keypad and responsive toposition of a human finger on the surface of the keypad, and anelectronic circuit adapted to receive signals from the IACK keypadindicative of keypad status and to produce an output in response tokeypad actuation by an operator. The electronic circuit is configured todetermine an intended combination key input based at least in part upona sensed position of a finger between centers of adjacent independentkey regions.

In some embodiments the device also has a key switch matrix responsiveto engagement of independent key regions, the electronic circuit beingconfigured to determine intended combination key input based on both thesensed finger position and a state of the key switch matrix. In somecases the grid of sense elements and the key switch matrix share someconductive traces of a printed circuit board.

The grid of sense elements may have a grid spacing wider than a spacingbetween centers of adjacent independent key regions and still provideacceptable resolution.

According to yet another aspect of the invention, an electronic devicehas a substrate carrying a first array of spaced apart, conductive traceelements and a flexible cover disposed above the substrate and carryinga second array of spaced apart, conductive trace elements. The first andsecond arrays together form a coordinate system, with the coverseparated from the substrate by an array of resilient, collapsibleelements and having an exposed, continuous surface. The first and secondarrays of trace elements also form a capacitive grid responsive topresence of a digit of an operator on the surface of the cover. Anelectronic circuit is adapted to sense a capacitive state of the gridand to determine a position of said digit upon the sensed capacitivestate.

In some preferred embodiments, the continuous surface defines keyregions of a keypad, and the electronic circuit interprets intendedkeypad input based at least in part upon the sensed capacitive state ofthe grid.

In some cases, the capacitive grid is responsive to a position of localdeflection of the cover toward the substrate, and the collapsibleelements comprise formations integrally molded to extend from a surfaceof the cover facing the substrate.

In an illustrated embodiment, the device is in the form of an IACKkeypad, with the exposed cover surface defining both independent keyregions and combination key regions.

According to another aspect of the invention, a keypad includes an outercover with an exposed, continuous surface defining key regions, a gridof sense elements underlying the surface of the cover and responsive toposition of a human finger on the surface of the keypad, and a singleswitch adapted to change state when any one of a multiplicity of the keyregions is pressed (preferably, when any key region of the keypad isdepressed).

In some embodiments, the keypad is an IACK keypad, with the exposedcover surface defining both independent key regions and combination keyregions, and the single switch adapted to change state when anyindependent key region is depressed. The independent key regions may beelevated above the combination key regions.

According to one aspect of the invention, an input device has a coverwith an exposed surface defining regions associated with correspondingdiscrete inputs, and a substrate below the surface. The cover carriesone array of a variable capacitance grid, and the substrate carriesanother, preferably perpendicular, array of the grid. The device alsohas an electronic circuit adapted to interpret large-scale capacitancevariations of the grid as a localized deflection of the cover toward thesubstrate in a region identified by the capacitance variation, and tointerpret small-scale capacitance variations of the grid as anorientation and extent of motion of a finger along the surface.

In accordance with one aspect of the invention, an at-a-distancemeasurement device is integrated into an IACK keypad. In one of itsembodiments, this measurement device is employed to increase thereliability and accuracy of an IACK keypad. By identifying the locationof the finger in addition to or independently from an associated matrixof switches, the errors that may arise from an ambiguous subset ofswitches in a combination key may be eliminated. In another embodimentthe measurement device is disposed beneath an IACK keypad to provide“mouse” functionality. In some preferred embodiments, the integratedsystem has the same number of electrical lines as the IACK device alone.In one embodiment two perpendicularly-oriented arrays are disposed ondifferent elements: one on the PCB and one on the underside of the IACKelement. In this embodiment, parasitic capacitive variations (betweenthe array intersections) are used for positioning of the finger for bothmouse and keypad functions, while physical displacement of the IACKelement creates capacitive variation that is relatively huge incomparison to the parasitic variation. Therefore, finger motion may beeasily distinguished from key activation despite the superimposition ofthe signals. In another embodiment the at-a-distance measuring deviceand the keypad matrix are integrated. In another embodimentpiezo-ceramic elements (disposed in a sheet across the surface ordiscretely) are used to generate a tactile response. Tactile responsemay also be provided by the same element used to vibrate the devicebecause the frequencies within this range are difficult for human fingerto localize.

Integrating a location measuring system and an IACK keypad can provideseveral advantages. For example, while in a mouse mode the IACK keypadsurface can provide stability for the finger in mobile situations. Thisis a serious issue because of the constant intermittent erratic motionsinherent in travel. For a user to accurately control a cursor of a smallhandheld device (such as a phone) while traveling by bus, train, car, orwhile walking is a frustrating task. Prominent reference elevations,placed along the surface of a touchpad or other cursor control locationmeasuring system can solve this problem by proving reference points tofinger location. The prominent reference elevations of some embodimentscan give the user tactile reference, enabling the user to bettermaintain hand position by providing a small ledge that mechanicallystabilizes the finger. When the finger is between elevations the supportis provided by the elevations that surround it, and when the finger isat an intermediate location over an elevation, the compliance of thefinger serves to capture the elevation within the flesh of the finger.By stabilizing the finger in this way, a high degree of accuracy may beprovided in travel situations that would otherwise be frustrating. Thedevice can be configured to output audio cues (such as a digitized voicesaying the letters and numbers) or visual cues (such as changing thecharacter displayed, especially in an oversized font, potentiallyfilling a large fraction of the screen) as the user moves their fingeracross the face of the device. The audio implementation is particularlyuseful for blind users and the visual version is particularly useful forthe sight-impaired. The invention can provide much needed consistencyand efficiency for a user while enabling access of both mouse and IACKkeypad functions without moving the hand.

According to another aspect of the invention, an IACK keypad having asubstrate carrying an array of sense elements arranged to change statein response to keypad operation, and a flexible (e.g., elastomeric)cover disposed above the substrate and having an exposed surfacedefining an array of independent key regions, with combination keyregions defined in interstices between adjacent independent key regions,also has an array of discrete snap elements extending between the coverand the substrate and spacing the cover from the substrate. The snapelements are each located between two adjacent independent key regionsand adapted to resiliently collapse as a non-linear response to localpressure against the exposed cover surface to provide tactile feedbackof keypad operation.

In some cases, the snap elements are located under the combination keyregions. In some cases, the snap elements are located between directlyadjacent independent key regions. By “directly adjacent” I meanindependent key regions not defining a combination key region directlybetween them, such as adjacent independent keys of adjacent columns in astaggered matrix. In some cases, the snap elements include snap elementslocated under the combination key regions and snap elements locateddirectly between directly adjacent independent key regions.

In some embodiments, each independent key region and each combinationkey region has four corresponding, spaced-apart snap elements disposedat its periphery, with each interstice between four adjacent snapelements corresponding to a key region. The snap elements are preferablyeach located equidistant between centers of adjacent independent keyregions and equidistant between centers of adjacent combination keyregions.

In some instances, each independent key region defines an exposedcontact pressure area, the keypad further comprising an array ofconductive pills between the substrate and cover. Each conductive pillis centered below a corresponding independent key region and extendslaterally farther (e.g., toward an adjacent combination key region) thanthe contact pressure area of its associated independent key region. By“contact area” I mean the area of the independent key region that actsas a button during operation, in the sense of transmitting force fromthe operator's finger to deflect the keypad cover. Such area does notinclude area which only comes into incidental, non-loading contact withthe operator's fingertip. Thus, substantially all (e.g., 90 percent) ofthe load applied by the operator during operation of a singleindependent key region is applied to the contact pressure area.

Some embodiments include an array of discrete snap elements extendingbetween the cover and the substrate and spacing the cover from thesubstrate. The snap elements are each located between two adjacentindependent key regions and are adapted to resiliently collapse as anon-linear response to local pressure against the exposed cover surfaceto provide tactile feedback of keypad operation.

In some cases the independent key regions comprise raised nubs withupper surfaces having distal edges that circumscribe their contactpressure areas, or are of diamond shape, with arms directed betweenadjacent combination keys.

In some configurations each pair of adjacent independent key regions hasthree of the snap elements disposed along a line segment disposed midwaybetween the pair of independent key regions (e.g., along a boundaryseparating the two independent key regions). Preferably, the three snapelements are equally spaced along the line segment, with one directlybetween centers of the independent key regions of the pair, and one ateither end of the line segment, at an interstice between four adjacentindependent key regions.

In some particularly preferred embodiments, the snap elements are ofelastomer (e.g., silicone) integrally molded with and extending from aback surface of the cover.

In some illustrated instances, the snap elements are of frustoconicalshape.

Preferably, the snap elements are advantageously arranged to provide asubstantially equal tactile feedback in response to pressure againstboth independent key regions and combination key regions. It is alsopreferable that the snap elements be constructed and arranged to requirea substantially equal normal activation force for both independent keyregions and combination key regions.

According to another aspect of the invention, an IACK keypad has asubstrate carrying an array of sense elements arranged to change statein response to keypad operation; a flexible (e.g., elastomeric) coverdisposed above the substrate and having an exposed surface defining anarray of independent key regions, with combination key regions definedin interstices between adjacent independent key regions; and an array ofdiscrete snap elements extending between the cover and the substrate andspacing the cover from the substrate. The snap elements are each locatedbetween two adjacent independent key regions and adapted to resilientlycollapse toward the substrate as a non-linear response to local pressureagainst the exposed cover surface to provide tactile feedback of keypadoperation. The snap elements are also each symmetric in shape about anassociated axis perpendicular to the substrate and intersecting thecover between adjacent independent key regions.

Preferably, the snap elements are frustoconical in shape, or of a shapeadapted to provide the same function in the same way as a hollow,volcano-shaped frustocone, and produce substantially the same non-linearbuckling response.

In some cases, the snap elements are of elastomer integrally molded withand extending from a back surface of the cover.

In some embodiments, each independent key grid space has at least fourcorresponding, spaced-apart snap elements disposed at its periphery,with each interstice between four adjacent snap elements correspondingto a key region. Preferably, the snap elements are arranged to provide asubstantially equal tactile feedback in response to pressure againstboth independent key regions and combination key regions.

According to another aspect of the invention, an IACK keypad has asubstantially planar substrate carrying an array of sense elementsarranged to change state in response to keypad operation, a flexiblecover disposed above the substrate and having an exposed surfacedefining an array of key regions arranged in rows, and at least onecontinuous, elongated snap element extending adjacent at least three keyregions of one row of key regions, between the cover and the substrateand spacing the cover from the substrate. The snap element is adapted toresiliently collapse as a non-linear response to local pressure againstthe exposed cover surface to provide tactile feedback of keypadoperation.

In some constructions, the keypad has multiple such snap elements in theform of elongated rails extending between adjacent rows of key regions.

The snap element may comprise a rib, for example, extending at an angle(of, e.g., 60 degrees) with respect to the plane of the substrate andconfigured to buckle in response to local pressure against the exposedcover surface.

According to another aspect of the invention, an IACK keypad includes asubstantially planar substrate carrying an array of sense elementsarranged to change state in response to keypad operation, and a flexiblecover disposed above the substrate and having an exposed surfacedefining an array of independent key regions arranged in rows andcolumns, with combination key regions between adjacent independent keyregions. The cover also has a back surface facing the substrate and heldaway from the substrate by collapsible snap elements between the coverand substrate, with the back surface carrying an array of conductivepills located beneath corresponding independent key regions. Eachconductive pill extends across the back surface of the substrate towardan adjacent combination key region center a lateral distance equal tobetween about 50 percent and 70 percent (preferably about 50 percent) ofa distance between the adjacent combination key region center and acenter of the independent key region corresponding to the pill.

In some configurations the conductive pills are cross-shaped, with armsextending toward multiple adjacent combination key regions.

Preferably, each conductive pill has a distal edge nearest the adjacentcombination key region substantially perpendicular to a line connectingthe adjacent combination key region center and a center of theindependent key region corresponding to the pill.

In some cases, the pills have contact surfaces facing the substrate thathave outer regions that slope away from the substrate.

According to another aspect of the invention, an IACK keypad has asubstantially planar substrate carrying an array of sense elementsarranged to change state in response to keypad operation, and a flexiblecover disposed above the substrate. The cover has an exposed surfacedefining an array of independent key regions arranged in rows andcolumns, with combination key regions between adjacent independent keyregions, and a back surface facing the substrate and held away from thesubstrate by collapsible snap elements between the cover and substrate.The back surface carries an array of conductive pills located beneathcorresponding independent key regions, with each conductive pill havinga contact surface facing the substrate that has outer regions that slopeaway from the substrate.

In some preferred embodiments, the conductive pills are cross-shaped,with arms extending toward multiple adjacent combination key regions andthe arms of the conductive pills comprising the sloping outer regions.

Preferably, each conductive pill extends across the back surface of thesubstrate toward an adjacent combination key region center a lateraldistance equal to between about 40 percent and 99 percent (morepreferably between about 50 percent and 90 percent, and most preferablybetween about 70 percent and 80 percent) of a distance between theadjacent combination key region center and a center of the independentkey region corresponding to the pill.

According to another aspect of the invention, an IACK keypad having asubstrate carrying an array of sense elements arranged to change statein response to keypad operation, and a flexible (e.g., elastomeric)cover disposed above the substrate and having an exposed surfacedefining an array of independent key regions, with combination keyregions defined in interstices between adjacent independent key regions,also has an array of discrete snap elements extending between the coverand the substrate and spacing the cover from the substrate. The snapelements are each located between two adjacent independent key regionsand adapted to resiliently collapse as a non-linear response to localpressure against the exposed cover surface to provide tactile feedbackof keypad operation, and are arranged to provide a substantially equaltactile feedback in response to pressure against both independent keyregions and combination key regions.

In accordance with another aspect of the invention, elastomeric conesare molded into the underside of an IACK element utilizing a novelmanufacturing method including a matrix of conical-shaped through holes.In accordance with another aspect of the invention, tactile feedbackelements are disposed at intermediate points between adjacentIndependent keys and may be comprised of elastomeric cones are moldedinto the underside of an IACK element. In accordance with another aspectof the invention, the tactile feedback elements of an IACK keypad arecomprised of a metallic element stamped to include arcuate elementsdisposed at intermediate points between adjacent Independent keys.

According to another aspect of the invention, a method of interpretingIACK keypad input is provided. The method includes sensing keypad inputcorresponding to a combined actuation of a plurality of independent keyregions of the keypad, and comparing the sensed input to defined sets ofindependent key inputs corresponding to combination keys. For sensedinputs found to correspond to a plurality of independent key regionsassociated with a combination key, a combination key input isregistered. For sensed inputs found not to correspond to any combinationkey, the sensed input is compared to recorded custom chorded keyassociations. For sensed inputs found to correspond to a recorded customchorded key association, a sequence of characters according to thecorresponding chorded key association is registered.

In some implementations, a sequence of characters determined solely bythe plurality of independent key regions of the sensed input isgenerated, for sensed inputs found not to correspond to any combinationkey or to any recorded custom chorded key association. In some cases,the sequence of characters is generated by arranging the independent keyregions of the input according to a predetermined order.

In some applications, an association between the sensed input and aselected string of characters is stored in readable memory, for sensedinputs found not to correspond to any combination key or to any recordedcustom chorded key association. Characters contemporaneously shown on adisplay when the input is sensed, for example, may define the selectedstring of characters.

In some embodiments, for sensed inputs found not to correspond to anycombination key, the method includes comparing the sensed input to aninput character last registered prior to the sensed input to determinewhether the last registered character is among the plurality ofindependent key regions of the sensed input, and, for last registeredcharacters found to be among the plurality of independent key regions ofthe sensed input, deleting that last registered character.

In accordance with another aspect of the invention, the electronics andaccompanying algorithms of an IACK keypad have been implemented tosimultaneously register the input from a plurality of keys as the meansfor a user to instantaneously input a specific sequences of numbers suchas Personal Identification Number (PIN), or access codes (such as atelephone number, followed by a PIN number). In accordance with anotheraspect of the invention an algorithm provides a mapping from inputs ofalphabetic keys to numeric key outputs as dictated by the correlationsof the standard 12 key telephone pad.

The invention can, in some aspects, taking advantage of the ability ofthe IACK keypads disclosed above to detect simultaneous input from anycombination of independent key regions, even non-adjacent ones. Thismethod is advantageous for providing a secure, yet fast, means to enternumeric codes, for applications such as: providing access to web sitesand other phone-based services and content; entering one's own telephonenumber followed by PIN as a means to access voice mail; and the like.

According to another aspect of the invention, a telephone has a keypaddefining alpha key regions corresponding to individual letters, andnumerical key regions corresponding to individual numerals, and anelectronic circuit connected to the keypad to receive input therefrom asvarious key regions are engaged by an operator. The electronic circuitis configured to translate alpha key input into numerical output in theform of a combination of numerals 2 through 9, based upon standardtelephone keypad letter-number correspondence. By “telephone”, I mean inone sense a device capable of accepting input from an operator andgenerating a corresponding code recognizable as representing a telephonenumber associated with the input. This would include, for example,stand-alone devices that generate a telephone number (e.g., by therecited transposition) but are not connected to a network. In a narrowersense, I mean a device connected to a telephonic network (eitherhardwired or wireless) for communication over the network.

In some embodiments the electronic circuit is configured to, in a firstmode, display an individual letter in response to engagement of aselected alpha key region, and to, in a second mode, display one ofnumerals 2 through 9 in response to engagement of the selected alpha keyregion, the displayed numeral selected according to standard telephonekeypad letter-number correspondence.

The electronic circuit is configured, in some applications, to registera sequence of letters as their associated alpha key regions are engaged,and, in response to additional input from the operator, transpose theregistered sequence of letters into a telephone number according tostandard telephone keypad letter-number correspondence. In someinstances the electronic circuit is further adapted to, in response tosaid additional input, initiate a telephone call using the telephonenumber.

Preferably, the electronic circuit is adapted to register numericaloutput according to the numerals associated with the numerical keyregions, such that numerical input is unaffected by transposition.

According to another aspect of the invention, a method of dialing atelephone is provided. The method includes entering a desired sequenceof alphanumeric characters including at least one alpha character. Thetelephone generates a corresponding sequence of numerals by transposingthe alpha character into one of the numerals 2 through 9 according tostandard telephone keypad letter-number correspondence.

In some cases, the method also includes instructing the telephone togenerate the corresponding sequence of numerals after the alphanumericsequence has been entered.

In many embodiments useful in English-speaking countries, for example,the desired sequence of alphanumeric characters is entered on a keypadincluding at least 24 individual key regions, each key regioncorresponding to a different alphabet letter.

In some embodiments, the desired sequence of alphanumeric characters isin the form of a pronounceable utterance and entered by pronouncing theutterance. For example, the sequence of alphanumeric characters maycomprise a series of alpha characters that spells a pronounceable text,such as “1-800-FLOWERS”. These embodiments are preferably implementedwith voice recognition algorithms that distinguish between pronounceabletext that identifies a number (such as “one, eight-hundred”) from thatwhich does not (such as “flowers”), and transposes only non-numericaltext, particularly when interpreting the number-identifying text as anumber generates a telephone number of reasonable length and format.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIGS. 1 and 2 are cross-sectional views of two keypad embodiments withintegrated location measuring systems.

FIG. 3 is a plan view of an integrated location measuring grid and keyswitch matrix, showing four different types of key switch grids.

FIG. 4 shows a keypad with a doped cover rather than exposed pills.

FIG. 5 shows a keypad without a traditional key switch matrix but with alocation measuring grid.

FIG. 6 shows a keypad with a location-measuring grid having one set oftrace elements on the underside of the flexible cover and a set ofperpendicular trace elements on the substrate.

FIG. 7A shows a keypad with snap elements formed by an array ofhigh-deformation type piezoelectric devices, while FIG. 7B shows akeypad with a single piezoelectric element between the cover andsubstrate.

FIG. 8 shows a keypad with a force-sensitive resistor between the coverand substrate.

FIG. 9 shows a keypad substrate with a single pair of electrical tracesproviding contact for all of the switches in the matrix.

FIG. 10 shows the underside of an IACK keypad cover with a firstconductive pill arrangement.

FIG. 11 is a cross-sectional view, taken along line 11-11 in FIG. 10.

FIG. 12 shows the underside of an IACK keypad cover with a secondconductive pill arrangement.

FIG. 13 is a cross-sectional view, taken along line 13-13 in FIG. 12.

FIG. 14 is an end view of a solid sheet of material from whichconductive pills may be stamped.

FIG. 15 illustrates switch grid pads configured for use with the coverof FIG. 12.

FIG. 16 shows the underside of an IACK keypad cover with a thirdconductive pill arrangement.

FIG. 17 is a cross-sectional view, taken along line 17-17 in FIG. 16.

FIG. 18 shows the underside of an IACK keypad cover with a fourthconductive pill arrangement.

FIG. 19 is a cross-sectional view, taken along line 19-19 in FIG. 18.

FIGS. 20A and 20B illustrate the deflection of the keypad covers ofFIGS. 17 and 19, respectively.

FIG. 21 is a partial perspective view of the underside of an IACK keypadcover.

FIG. 22 shows a keypad with pills placed directly beneath independentkey regions.

FIG. 23 is a schematic representation of a telephone electronic circuit.

FIG. 24 is a cross-sectional view of a two-part mold for molding theunderside surface of the keypad cover of FIG. 21.

FIG. 25 is a perspective view of a first tactile feedback sheet for useunder a keypad cover.

FIG. 26 shows a keypad with a second tactile feedback sheet.

FIG. 27 is a face view of the feedback sheet of FIG. 26.

FIG. 28 is a perspective view of a smoothly contoured IACK keypadsurface.

FIGS. 29 and 30 are perspective and face views, respectively, of anotherIACK keypad surface.

FIG. 31 shows a preferred layout for an alphanumeric IACK keypad for atelephone.

FIGS. 32 and 33 are cross-sectional views, taken along lines 32-32 and33-33, respectively, of FIG. 31.

FIG. 34 is a layout of a QWERTY keypad, with columns of independent keysarranged diagonally.

FIG. 35 illustrates an algorithm for storing and recognizing combinationinputs.

FIG. 36 illustrates an algorithm for reverse mapping alphanumeric datato generate a numerical output.

FIG. 37 shows a standard telephone keypad letter-number correspondence.

FIG. 38 is a perspective view of a third tactile feedback sheet for useunder a keypad cover.

FIG. 39 shows a keypad with a molded tactile feedback sheet having anarray of conical snap elements.

FIG. 40 shows a scan algorithm for use with an IACK keypad.

FIG. 41 shows a printed circuit board with traces extending at a45-degree angle with respect to the key switch matrix.

FIG. 42 shows an arcuate arrangement of independent key region centerssuperimposed upon a rectilinear switch grid matrix.

FIGS. 43 and 44 and face and perspective views, respectively, of amobile telephone with an IACK keypad.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring first to FIG. 1, a flexible membrane keypad element 10 extendsover a printed circuit board (PCB) 12 having both a common key switchmatrix 5 and an at-a-distance location measuring system 20. Key switchmatrix 5 is disposed on the upper surface of PCB 12 and hasperpendicularly oriented conductive traces whose intersections formswitch grid pads 18 that are momentarily connected by contact withconductive pills 16 carried on the lower surface of membrane 10 directlyabove corresponding pads 18. Membrane 10 has an undulating upper surfacethat forms elevated independent key regions 2 separated by valleys thatcorrespond to combination keys. Conductive pills 16 may be of a solidmaterial impregnated with a conductive material, such as carbon, or of anon-conductive material (such as the material of membrane 10) with aconductive ink or coating. In this embodiment measuring system 20includes two overlapping arrays of linear elements (shown here asmutually orthogonal planar arrays 22 and 24, each printed as a layer ofprinted circuit board 12. Such measuring devices are employed, forexample, in touchpads and other two-dimensional position-responsivecomputer input devices. With the grid spacing as shown, measuring system20 is employed to increase the accuracy of the IACK keypad by helpingwith the interpretation of indefinite keypad manipulation to determineintended individual and combination keypad input. For example, inkeypads with combination keys corresponding to the simultaneousactivation of four independent keys, it is common for an inaccuratefinger placement to actuate only two adjacent keys (especially inembodiments utilizing discrete key switch technologies), resulting inambiguity. In keypads with combination keys corresponding to thesimultaneous activation of two independent keys, it is common for aninaccurate finger placement to actuate only one of the two independentkeys, resulting in erroneous individual key output. For example, it ispossible to have combination keys located at or beyond the edges of anIACK keypad and to generate inputs associated by such keys when twoadjacent independent keys in a column along the edge are actuatedtogether, although this can, in some cases, result in an increased errorrate. However, by independently determining the position of the fingerwith location measuring system 20, it becomes possible to correctlyresolve such inaccuracies and correctly interpret the intended input.For example, when a 4-key-based output is desired the finger will bepredominantly located over the associated interstitial graphiccorresponding to the combination key, yet due to an angling of thefinger or physical anomalies of the user's finger, the pressure pointsmay include only the lower two switch grid pads 18. In this case, theambiguity may be resolved by location measuring system 20, even with arelatively low resolution. Relatively inexpensive analog to digitalconverters may be employed to provide resolution on the order of ¼finger width, or about 10 to 20 times lower resolution than in typicalcommercially available location measuring systems. Likewise, using thistechnique, an actuation of a single key can be used to accuratelyinterpret user-intent in an IACK keypad, with the location measuringsystem 20 providing location information and an actuation at any one ofswitch grid pads 18 providing “go/no go” information. This includes anon-traditional key switch matrix 6 in which a single contact may bemade at any location across the keypad as shown in FIG. 9.

Measuring system 20 also provides integrated “mouse” (cursor control)functionality with IACK keypad scanning in a single PCB 12. In thisembodiment, location-measuring system 20 operate in two modes. In afirst mode it provides position location information regarding thelocation of the finger with respect to an IACK keypad surface, toimprove the accuracy of IACK combination key manipulationinterpretation, as discussed above. In a second mode, it is employed toorient a cursor on the display of the product attached to the keypad.The user may efficiently transfer between ‘mouse mode’ and ‘keypad mode’with the touch of a button (not shown), for example. Enabling the userto selectively turn off either combination key functionality orindependent key functionality in an IACK keypad can have otheradvantages: in gaming applications, for example, the combination keysmay assume a directionality function; for persons with a palsy of othersuch muscular disorder it eases accessibility to the function of choice;etc.

In some configurations, the input and output lines of the locationmeasuring system and traditional key switch matrix 5 are advantageouslytied together, so as to minimize the pin count, or even to not increasethe overall pin count beyond what is required by a traditional keypadalone, for example.

Referring to FIGS. 2 and 3, the dashed lines are traces submerged withinthe PCB are shown as dashed lines, traces at the PCB surface are shownas solid lines, and vias or holes connecting the two layers are shown asdots. Integrated vertical array 23 is disposed at the surface of PCB 12(to reduce the number of vias) and forms both one-half of key switchmatrix 5 and the vertical array of the location measuring system.Likewise, integrated horizontal array 25 forms the other half of keyswitch matrix 5 and the horizontal array of the location measuringsystem. In this case, array 25 is disposed within PCB 12. Switch gridpads 18 are located at each junction of arrays 23 and 25, and eachconsists of an interdigitated arrangement of exposed elements on thesurface of the PCB, thereby forming a capacitive grid element forlocation measuring system 20 with a plurality of switch grid pad 18halves integrated within it. Each column of FIG. 3 shows a differentdesign for pads 18. The leftmost column shows switch grid pad 18 withthe contact elements designed for use with a snap dome switchtechnology. The column second from the left shows an interdigitated padwith a single via. The column second from the right shows a spiralpattern and a single via. The rightmost column shows first elements 19(shown three in number for each grid pad) interconnected by a shortvertical element disposed on the surface of the PCB on the left mostelement of array 23, and a short vertical element disposed within thePCB on the other two elements of array 23. Second elements 21 areinterdigitated with first elements 19 and connected to each other by anintegrated horizontal array 25 through associated holes or vias 27. Ineach case the elements of switch grid pad 18 are symmetrically disposedwith respect to the elements of location measuring system 20, therebyproviding a self-canceling signal and not compromising accuracy of thelocation measuring system 20 despite the integration of the key switchmatrix, such that a consistent output is measured independent of thedirection from which the finger approaches the switch.

Input 31 is comprised of the signals injected into integrated horizontalarray 25, and output 33 is comprised of the signals received byintegrated vertical array 23. Thus, the total number of pins required ofa microprocessor or an analog-to-digital converter that conditions thesignal for input to a microprocessor is the same as needed for thetraditional key switch matrix 5 alone.

Changes in parasitic capacitance across switch grid pad 18 may also beused to detect approach or proximity of finger or conductive pills 16.This can provide additional information necessary to resolveambiguities, for example.

In the keypad of FIG. 4, IACK element 10 has no conductive pills as inthe embodiment of FIG. 1, but has instead been doped with aforce-sensitive material 13, such as a conductive non-contactingparticulate. For example, material 13 can be such as those that providea quantum tunneling effect as developed by Peratech Limited ofDarlington, County Durham, England.

In the embodiment of FIG. 5, an IACK keypad is implemented without atraditional key switch matrix. Location-measuring system 20 provides thefunction of both cursor control and keypad entry. The high degree ofnon-linearity of the capacitive measurement and ability of the device toboth determine a maximum threshold for any given user and to determinethe extent of the finger through measurements at proximate intersectionsallow this embodiment to operate without any distinct keypad switchmatrix. As the finger approaches and thereby increases the magnitude ofthe capacitive measurement, the system determines the approximate sizeof the finger by comparing adjacent intersections, on a relative scale.This is to say that as the finger tracks across the keypad from onelocation to another, across several nodes, a range of high and lowcapacitive values is established on those occasions when the finger doesnot substantially change in elevation. This range is then compared to areference, such as a look-up table on an absolute scale, establishingthe size of the person's finger and thereby determining an appropriatecapacitance measurement level that should be measured to recognize anintended input (e.g., a pressing of a key region, based on the locationof the finger at the moment the appropriate intended input threshold isreached and the size of the finger.

In the embodiment of FIG. 6 the integrated horizontal array 25 isdisposed within PCB 12 and the vertical array 23 is disposed, preferablyprinted in conductive ink, on the lower surface of IACK element 10.Horizontal array 25 may also be disposed at the surface of PCB 12 andcovered with a thin non-conductive sheet of material, such as 0.010 inchof KAPTON (generically, polyimide), available from DUPONT. Theembodiment of this figure advantageously increases the capacitivevariation measured upon actuation of a key, with respect to theembodiment of FIG. 5. As a finger moves across the surface of IACKelement 10 (without pressing keys) the device measures parasiticcapacitance variations to provide coordinate location information.Pressing a desired character in keypad mode causes a much greatercapacitance variation, because the traces of the capacitive array aredisplaced relative to each other. This high degree of capacitive changeis of a different order than those measured by parasitic variation andthereby clearly indicates that a key actuation is intended. The systemthen registers the character identified by the parasitic variationsmeasured just prior to the large, actuation-indicative variation. Thetwo measurement systems are thus employed in concert to provide aparticularly robust cursor control and keypad system. One of theadditional advantages of this design is that it can be configured toneed fewer microprocessor pins than a traditional keypad matrix, despiteproviding the additional functionality. For example, the number,placement and spacing of the traces of the array need not correspondwith the key regions of the keypad in some embodiments, as illustratedby the placement of the rightmost element of array 23 in the figure. Thespacing of the capacitance grid may be larger, for example, than thespacing of the adjacent independent key regions.

FIG. 7A shows a keypad with snap elements formed by an array ofhigh-deformation type piezoelectric devices 30 as disclosed in U.S. Pat.Nos. 5,781,646, 5,849,123 and 5,831,371, the contents of which areincorporated herein by reference. This embodiment can add energy to thedevice as a consequence of its use, and a high degree of tactilefeedback. However, this embodiment can exhibit a plurality of tactile“clicks” associated with a single combination key output. FIG. 7B showsan array of devices 30 formed as a single piezoelectric element 32disposed below the entire IACK element 10 and above location measuringsystem 20. This embodiment can provide several advantages, such as theability to provide a single “click” for combination key input, as wellas the ability to provide “call received” vibrations audible signals byappropriately activating displacement/voltage transducer element 32 asdetailed in the prior art.

FIG. 8 shows a keypad with a force-sensitive resistor 32 a, such asprovided by Interlink of Camarillo, Calif., disposed between IACKelement 10 and a mechanical backing 33. Snap elements may be designed tobe very readily collapsed, replaced by a bellows with a release valve ata predetermined pressure, or eliminated entirely as shown, becausetactile feedback is provided by vibration element 40, which is actuatedbriefly by controller 42 to indicate that an output has been receivedfrom the keypad. The vibration element 40 shown is a vibratory motor,such as are commonly employed in telephones, pagers and the like, toindicate an incoming call or page.

FIG. 9 shows an IACK keypad PCB 12 with a single pair of electricaltraces 69 a and 69 b providing contact for all of the switches in thematrix.

Referring now to FIGS. 10 and 11, an IACK element is equipped withconductive pills 16 with flat outer contact surfaces 16 a in the shapeof crosses, with distal ends 52 of the arms 17 of the crosses extendingtoward associated combination key regions 3. Each pill 16 is positioned,for example, directly beneath an individual key region 2 of the keypadand extending over about distance d₁ of about 40 percent of the distanced₂ from the center of the conductive pill 16 to the center of thecombination key region 3 toward which it extends. In this embodiment,each distal edge 52 is located approximately along segments connectingthe centers of the most adjacent snap elements 14. The remaining edgesof conductive pills 16 are preferably displaced at least one-half of asnap element stroke length ‘s’ from each adjacent snap element 14, where‘s’ is defined as the vertical distance that snap elements 14 extendbeyond conductive pills 16. Contact zones 67 are the area of theindependent key regions that acts as a button during operation, in thesense that they transmit force from the operator's finger to deflect thekeypad cover, and do not include area which only comes into incidental,non-loading contact with the operator's fingertip. Thus, contact zones67 transmit substantially all (e.g., 90 percent of) the load applied bythe operator during operation of a single independent key region. Therelationship between contact zones 67 and preferred pill shape isexplained with respect to FIGS. 20A and 20B. The exposed, upper surfaceof the keypad shown in FIG. 11 corresponds with the key region contourshown in FIG. 28.

FIGS. 12 and 13 illustrate a different configuration of conductive pills16. In this embodiment, pills 16 each form an extended cross, with arms17 of the cross extending toward combination key regions 3 further thanshown in the embodiment of FIGS. 10 and 11. In this instance, arms 17 ofthe cross extend toward adjacent combination key regions 3 approximately75 percent of the distance from the center of the conductive pills 16 tothe center of the combination key regions 3, with distal arm edges 52disposed beyond adjacent snap elements 14. This can be employed tosignificant advantage, as explained with respect to FIG. 20. Centralarea 54 of each pill is predominantly flat and parallel to the plane ofthe keypad, with arms 17 tapering at about 10 to 20 degrees with respectto this plane. The remaining edges of conductive pills 16 are displacedat least one-half of the stroke length from snap elements 14, where thestroke length is defined as discussed above with respect to FIG. 11.

FIG. 14 shows an end view of a sheet 58 of a solid conductive materialfrom which the conductive pills 16 of FIGS. 12 and 18 may be stamped, asan alternative to printing the surface of a molded IACK element 10 withconductive ink. Sheets 58 of carbon-doped foamed or elastomericmaterial, or material otherwise rendered conductive, are extruded orotherwise molded such that one or more cross-sections have an undulatingsurface as shown. Individual pills 16 are then stamped or punched fromsuch a sheet. Symmetry of the stamped pills can enable the pills to beoriented either up or down during manufacture, with the elastomericmaterial conforming as needed to accommodate, thereby easing themanufacturing process.

FIG. 15 illustrates switch grid pads 18 configured for use with theconductive pills 16 of the embodiment of FIG. 12, with light emittingdiodes 56 placed in combination key regions 3 between the grid pads.

Referring now to FIGS. 16 and 17, an IACK element 10 has snap element 14located under combination key regions 3. Conductive pills 16 are shownbelow independent regions 2. In this example the top surface of thekeypad is as shown in FIG. 29. Preferably, distal corners 52 shouldpresent a flat edge to the combination key area 3. In this embodiment, arectangular shape with chamfered corners has been selected. Each pill 16is positioned, for example, directly beneath an individual key region 2of the keypad and extending over about distance d₁ of about 40 percentof the distance d₂ from the center of the conductive pill 16 to thecenter of the combination key region 3 toward which it extends, on aline connecting adjacent key region centers. The exposed, upper surfaceof the keypad shown in FIG. 17 corresponds with the key region contourshown in FIG. 29.

Analogous to FIGS. 12 and 13, FIGS. 18 and 19 show the pills 16extending farther toward the center of combination region 3, but withthe peripheral regions of the pill sloped away from the PCB 12. In thiscase pills 16 are shown with a flat, horizontal central area 54, but theentire contact surface of the pill 16 is, in other embodiments (notshown), sloped or curved to produce the desired result. Snap elements 14are as described above.

FIGS. 20A and 20B illustrate the deflection of the keypad cover to causea pill 16 a associated with a depressed key region 2 a to make contactwith PCB 12, while an adjacent pill 16 b associated with another keyregion 2 b tilts slightly with respect to the PCB but does not makecontact. As in the proceeding figures, the cross sections are takenalong the major axis of the pills. The pills of FIG. 20A are as in theembodiment of FIGS. 10 and 16, while the pills of FIGS. 20B are slopedas in the embodiment of FIGS. 12 and 18. If the user wants the characterprinted on key region 2 a, she needs to cause pill 16 a to contact PCB12; if she wants the character printed on key region 2 b, she needs pill16 b to contact; and if she wants the character printed on thecombination key region 3 between them, she needs both pills 16 a and 16b to make meaningful engagement with the PCB. In both examplesindependent key region 2 b has been slightly deflected, partiallybecause of necessary entrainment due to bending of the common membraneforming them, and partly due to inaccuracies inherent in normal use.Therefore, if the facing edges of the pills spanning a combination keyregion are too far apart, it is possible for very small fingertips todeflect the surface of the keypad corresponding to the combination keyregion without engaging both pills and therefore not registering thedesired combination key input. Conversely, if the facing edges of thepills between two directly adjacent independent key regions are tooclose together, then the user may accidentally cause an adjacentindependent key to strike when depressing only a single independent keyregion, registering a combination key input in error. The illustratedembodiments solve this dilemma by making the pills effectively bothlarge and small. By sloping the distal regions of the contact surfacesof the pills, as in FIG. 20B, they may be made larger and thereforeprovide reliable operation with both small and large fingers. Thisimprovement also helps to enable independent key regions 2 to be maderelatively small, while allowing the pills to remain relatively large.

FIG. 21 illustrates a two-dimensional array of equally spaced snapelements 14, each positioned approximately midway between the conductivepills 16 associated with two adjacent individual key regions 2. In thisembodiment, snap elements 14 are frustoconical, but it should beunderstood that variations to this specific shape will provideapproximately the same non-linear buckling effect. Snap elements 14 forma staggered array, with each interstice between snap elements containingeither a pill 16 associated with an individual key region 2, or an emptyspace associated with a combination key region. Each individual andcombination key region (i.e., each snap element interstice) is equallyconfigured with respect to the number of adjacent snap elements andtheir proximity, such that the user experiences a similar tactileresponse from both individual and combination key actuations as an equalnumber of snap elements 14 are compressed during operation of either.Pills 16 are shown as circular pucks in this illustration, but can be ofthe other shapes described above.

With the embodiment of FIG. 22, by contrast, tactile feedback for eachcombination key region 3 is provided by four, equally spaced, adjacentsnap elements, while tactile feedback for each individual key isprovided essentially by a single associated snap element 14 locateddirectly beneath the individual key region 2. Each snap element 14surrounds an associated conductive pill 16. This arrangement can beconfigured to provide a combination key actuation force of up to fourtimes greater than individual key actuation force, if such is desiredfor a particular application. For many applications, however, it will bedesirable to provide all key regions with a similar tactile feedbackresponse, as is provided by the embodiment of FIGS. 2 and 21, forexample, in which snap elements 14 are each disposed approximatelyequidistant between two adjacent individual key switches. In this case,snap elements 14 can be cross-shaped.

FIG. 23 shows a schematic of a mobile telephone control circuit forperforming the functions of a mobile phone, including those keypadcontrol algorithms disclosed herein. At its core is a telephoneprocessor 89, such as a chip ML20xx, available from Mobile Link of SantaClara, Calif. Flash memory 90, static random access memory 91 and liquidcrystal display 92 are connected through a bus to an ARM RISC (ReducedInstruction Set Computer) processor 95 of chip 89 that provides userinterface and protocol processing. Direct lines connect the systemconnector 93, SIM (Subscriber Identity Module) 94 and the keypad 100. AnOak digital signal processor (DSP) 99, also located on chip 89, providesthe physical layer for processing speech through a microphone 97 andspeaker 98 where it is transmitted and received by dual band RF unit 96.

Referring now to FIG. 24, a mold half 44 for forming the underside of anIACK element with integrally molded snap elements such as the ones shownin FIG. 14, consists of a fixed plate 45 that defines cavities 46 formolding the outer surfaces of each snap element, and a moving plate 47with roughly conical projections 48 that form the inner surfaces of thesnap elements. The two mold plates are held together as the resin isintroduced and cooled, and then separated to enable removal of themolded snap elements from cavities 46. Cavities 48 are also provided inplate 45 for holding conductive pills as inserts during molding. Movingplate 47 and fixed plate 45 may be permanently joined if thecross-sections through cavities 46 perpendicular to resin flow decreasein area toward the ends of the cavities, enabling pulling of the moldedsnap elements from their cavities without separating the mold halves.

FIG. 25 shows a tactile feedback structure for an IACK keypad having anarray of linear rails 62 molded with a common base sheet 63 andextending at an angle of approximately 60 degrees with respect to thebase sheet. Alternatively, rails 62 may be coiled or curved to meanderacross the face of sheet 63 like a snake. This embodiment providesnon-linear tactile keypad feedback over the entire surface of an IACKkeypad. An adhesive may be used to affix the sheet to the printedcircuit board, with holes 65 providing clearance for pills of the keypadto contact the PCB. Or, rails 62 may be integrally molded, complete orin sections, with the underside of an elastomeric keypad cover. Adheringthe distal ends of the rails to the opposing surface (of the keypadcover or PCB) prevents deformation of the center of the IACK keypadunder ranges of temperature and humidity and also provides a stablereference to the distal ends of the feedback elements.

FIG. 26 shows a side view of a keypad with a tactile feedback element210 in the form a stamped metallic sheet placed between cover 10 and PCB12. Sheet 210 is stamped to form arched segments 212 extending out ofits plane to form snap elements. In this embodiment, the back side ofthe sheet is in face-to-face contact with the back of the IACK element10, with the distal portions of the arched segments adjacent the PCB 12.As shown in FIG. 27, arched segments 212 are arranged in rows andcolumns between stamped apertures 214 that provide access of theconductive pills 16 to the PCB 12.

Referring next to FIG. 28, ergonomically friendly IACK keypad 80 has acontinuously undulating surface, and markedly does not presentcombination key regions 3 as being at visible interstices of independentkey regions 2. Instead, combination key regions 3 appear as completelyindependent entities (although they remain interstitial in function).There are no visible features extending into the visible combination keyregions 3 to indicate any relationship to the layout of independent keyregions. In this example, combination key regions 3 are smoothlycontoured, visibly bounded oval regions, each bearing a centrallylocated legend. Individual key regions 2 are not delineated, therebyproviding a visually clean and simplified context for increasedlegibility, and the traditional telephone key layout is created throughuse of predominantly graphical elements. The graphical elements may beslightly depressed and/or produced with a “two-shot” molding process inwhich the elements that define the combination key regions 3 (or of thetraditional telephone key layout alone) are molded first in one color,with the balance of the keypad molded in a second color.

FIG. 29 shows an IACK keypad 82 in which combination key regions 3 havebeen maximized as circular or oval regions, and the independent keyregions 2 consist of diamond shapes 64 disposed in voids between them.As in FIG. 28, this embodiment does not present combination key regionsas the intersections of independent keys. Instead, the combination keyregions appear to be independent entities. The expanded circular or ovalregions associated with combination key regions 3 are depressed in abowl-like shape by approximately 0.10 to 0.50 millimeter at theircenters, as measured from a neutral plane defined relatively sharptransitions at their edges. Referring also to FIG. 19, the elevatedportions are diamond-shaped nubs 64, extends above the neutral plane byapproximately 0.30 to 1.0 millimeter. Thus, the overall distance d₃ fromthe top of diamond-shaped nubs 64 to the bottom of the circular or ovalregions representing the combination key regions 3 is approximately 0.70to 1.5 millimeters. The tops of nubs 64 are predominantly flat, withslight curvatures. Combination key region 218 is equipped with a pair oftactile locating nubs 101, such as are employed to indicate the number“5” on many standard keypads. In addition, two additional locating nubs103 are located just outside the keypad grid, between the fourth andfifth rows of combination key regions (i.e., aligned with the fifthindependent key region row) as counted from the far end of the keypad.These locator nubs can be located by touch to assist in use of thekeypad in the dark, or by the vision impaired.

FIG. 30 also shows, in dashed outline, the underlying grid associatedwith the independent keys as determined by the switch matrix beneath thekeypad cover, to show that the exposed surface is void of delineationsof this functional grid, as viewed by an operator. Instead, the coversurface appears as a matrix of independent and combination key regions,as defined by delineations or sensible features not aligned with theunderlying grid.

FIGS. 31-33 show an IACK element 10 with a traditional telephone layoutformed by numerical columns of combination key regions 3. The firstnumerical column 70 (with 1,4,7,*) is separated from the secondnumerical column 72 (with 2,5,8,0) by a column of unrelated characters74 (here shown with punctuation symbols ‘?’, ‘@’, ‘-’ and ‘/’). Thispattern is repeated, with a second punctuation column of characters ‘)’,‘:’, ‘'’ and ‘.’ between the second and third numerical columns. Thewidths of the legend areas of adjacent combination key columns (e.g. 70and 74) are different in size, varying from wide (column 70) and narrow(column 74). A cross-section through directly adjacent independent keyregions 2 (FIG. 32) shows a regular key region spacing, while across-section through directly adjacent combination key regions 3 (FIG.33) shows alternating key region widths. Preferably, the width ‘X’ ofthe space between directly adjacent independent keys 2 is about half thewidth of a human finger or less, and the coloration of the legendregions used to identify the characters of the columns alternate, suchas in contrast from dark to light.

FIG. 34 shows an IACK keypad with columns of independent key regions 2and columns of combination key regions 3 disposed along a 45-degree biaswith respect to the user (i.e., with respect to a normal keypadorientation as defined by legend orientation). This embodiment increasesthe number of independently actuatable keys that may be disposed in ahorizontal line (as defined by normal keypad orientation) byapproximately 40 percent over some earlier IACK keypad implementations,thereby significantly reducing the width of a keyed product, especiallythe traditional QWERTY layout shown.

FIG. 35 shows an improved method for interpreting input in the form of along string of characters (LSC), such as a phone number, security code,Personal Identification Number (PIN; an access code used to identify anindividual prior to a system providing access or service) or the like,taking advantage of the ability of the IACK keypads disclosed above todetect simultaneous input from any combination of independent keyregions, even non-adjacent ones. This method can be advantageous forproviding a secure, yet fast, means to enter numeric codes, forapplications such as providing access to web sites and other phone-basedservices and content; entering one's own telephone number followed by aPIN as a means to access voice mail; and the like. These algorithms,referred to as the LSC function, can be adapted to simultaneouslysatisfy the following needs: 1) create a sufficiently complex input toprovide a reasonable level of security; 2) satisfy the minimalrequirements of PIN access codes in a wide variety of applications; and3) allow near-instantaneous input of LSCs, whether user-defined orsystem defined.

In step 100 the system scans the keypad electronics for an indicationthat two or more independent keys are engaged at any particular time. Instep 102 the system displays a character as the consequence of thesystem identifying a defined combination key corresponding to the sensedcombination, such as on a local display. Preferably, the user need notperform any separate task to access LSC functionality; simply engagingan undefined combination of at least two unrelated independent keys fora predetermined period of time prompts the system to access the LSCfunctionality. If the system detects an undefined combination, thesystem proceeds to step 104. In the event that the system had justpreviously registered an individual or combination key prior toidentifying an undefined combination and a “keyup” is not registered(i.e., the operator has not stopped pressing the keypad), the systemdeletes the previously entered character.

In step 106 the system determines if the undefined combinationcorresponds to a stored LSC. If previously stored, then the system poststhe associated LSC to the display in step 108. If the undefinedcombination has not been previously stored as corresponding to an LSC,the system determines in step 110 how many characters were registered onthe display when the undefined combination was sensed. If characters areregistered, but too few to be a valid PIN number (for example, one tothree), then the system informs the user that PINs must be at least fourcharacters long and continues to scan the keypad in step 100.

If there are no characters on the display, then the system proceeds togenerate a pseudo-random LSC based on the inputs provided. In step 111the system orders the independent key inputs (in this embodiment,combination keys are not read as they are when establishing definedcombinations) into a predetermined order that is independent of theorder in which the individual key inputs were sensed. One such orderwould be alphabetical. Another (which encompassed punctuation symbols)is to sort by ASCII value. This ordering is likely to change the orderin which keys were acquired by the system. In step 112 the systemgenerates an LSC string, preferably all-numeric and at least 8characters long. If a simple concatenation of the ASCII values resultsin too short an LSC, the values can be added together and the resultappended. There are numerous ways to generate an appropriate,psuedo-random numeric sequence from a set of inputs. If the result istoo long, it may be truncated.

In optional step 114 (useful if a phone call is in process, forexample), the system determines the identity of the other party bychecking caller ID or simply looking up the identity of the other partyin a stored address book. If, in step 110, it is determined that theuser has already entered a significant LSC into the display, (in thisexample four or more) then the system stores that undefined combinationinto memory so that the associated LSC may be provided by step 108 inthe future. In step 118 the LSC, whether defined by the user or thesystem, is posted to the display 92. In the case of a system-definedLSC, it may post a reference identifier, such as “PIN#3”, or (if step114 has been implemented) a party-specific identifier, such as “Bank XPIN.”

FIG. 36 shows an algorithm, embedded in a telephone, that provides areverse mapping from inputs of alphabetic keys to numeric key outputs asdictated by the correlation of the standard 12 key telephone pad (i.e.,standard telephone keypad letter-number correspondence, as shown in FIG.37) that simplifies the task of dialing telephone numbers provided in analphanumeric format, such as “1-800-PATENTS.” Such numbers havelong-been frustrating for while they are easy to remember, they are hardto dial. However, reverse mapping has special applicability to IACKkeypads because while they provide a telephone keypad, in many instancesthey do not provide a correlation between alpha and numeric characters.

In step 120 the user inputs alphanumeric data into the telephone. Thismay be done with a traditional keypad, an IACK keypad, or orally. Instep 122 the user signals the desire to “dial” a telephone number bypressing a key or by speaking a pre-designated word. Steps 120 and 122may be transposed, especially in the oral case. In steps 124 and 126, ineither order, the telephone passes numbers through without modification,while re-mapping the alpha characters by the standard alphanumerictelephone correlation shown in FIG. 37. For example, when any one of theletters “A”, “B”, or “C” is pressed, the output is the number “2.” Instep 128, the output from the algorithm is purely numeric, consistingentirely of combinations of the numerals 0-9.

FIG. 38 shows an elastomeric sheet 220 that provides tactile feedbackover an entire IACK keypad surface with discrete elements 222 thatextend, with the keypad assembled, between the cover and substrate.These elements 222 extend perpendicularly with respect to the base ofsheet 220 (as shown), to operate in a pure buckling mode as the cover ispressed against the substrate, or may be canted. Elements 222 may besolid cylinders or vertical tubes.

FIG. 39 shows snap elements 14 molded with a common sheet 61 that isseparate from IACK element 10. Snap elements 14 are conical with theirnarrow ends 230 directed downward, away from cover 10. Additionalthickness is provided at narrow ends 230, forming a block of material toincrease the “snappiness” or crisp feel of the tactile feedback providedby the domes.

FIG. 40 shows a scan algorithm that enables a particularly slow clockscan rate, thereby saving energy. As soon as one switch of the keypad isactivated, the scan is limited to adjacent keys. If a second key switchis activated within the wait time, the system searches only rows (orcolumns) above and below (adjacent to) the actuated pair. This iscontinued until an individual key is actuated for the duration of thewait time, or until opposing diagonals are detected.

FIG. 41 shows a printed circuit board 12 with the traces 226 at a45-degree angle with respect to the board outline in the keypad gridarea. The dashed lines represent traces connected with the center ringsof domed snap switches 228. The solid lines represent traces connectedwith the peripheral rings of those switches. Because individual keyslocated at adjacent opposing diagonals define combination keys, thislayout provides a simplified recognition algorithm. This hardware changeredefines the software so that simultaneous output from adjacent tracesindicates combination key output.

In FIG. 42, the rows of independent key regions 2 have been skewed tofollow arcs defined by radius “R”, such as to help to identify locationacross the keypad by touch, while their corresponding key switch pads 18remain arranged along orthogonal rows and columns, resulting in avertical offset “L” between centers of the independent key regions 2 andtheir switch pads 18 in certain columns. In far left and right columns,the independent key regions are slightly above their switch pad centers,in face view, while in the center column the opposite shift obtains.This keeps the switch matrix spacing constant, even though the spacingbetween diagonally adjacent independent key regions varies.

Referring now to FIGS. 43 and 44, a mobile telephone 250 incorporatesthe keypad cover 82 of FIGS. 29 and 30, and a display 92 for displayingalphanumeric text.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

1-20. (canceled)
 21. A touch-sensitive input device comprising anexposed, continuous surface defining a planar area; and a grid ofcapacitive sense elements coextensive with the area of the exposedsurface and responsive to engagement of the exposed surface by anoperator to establish a position of said engagement on the exposedsurface, wherein the exposed surface varies in elevation across itsplanar area to form a series of tactile features, and wherein theexposed, continuous surface is permanently affixed to the grid of senseelements; and an electronic circuit configured to interpret large-scalecapacitance variations of the grid as an intended input from theoperator in a region identified by the capacitance variation, and tointerpret small-scale capacitance variations of the grid as a positionof engagement of the exposed surface by the operator.
 22. The inputdevice of claim 21 wherein the tactile features comprise elevated nubs.23. The input device of claim 22 wherein said elevated nubs extend atleast about 0.75 millimeter from adjacent regions of the exposedsurface.
 24. The input device of claim 22 wherein said surface carrieslegends associated with said tactile features.
 25. The input device ofclaim 21 wherein said tactile features define distinct regions of thesurface corresponding with associated alphanumeric characters.
 26. Theinput device of claim 25 configured to output a sequence of alphanumericcharacters as corresponding tactile features of the surface are engagedsequentially.
 27. The input device of claim 21 comprising an IACKkeypad.
 28. The input device of claim 27 wherein the tactile featurescomprise nubs defining independent key regions of the IACK keypad. 29.The input device 27, wherein the electronic circuit is configured totemporarily display alphanumeric characters on a screen as an operatortraverses the exposed surface, the displayed alphanumeric charactersselected to correspond to a position of engagement of the exposedsurface by the operator. 30-79. (canceled)
 80. An IACK keypad comprisinga substantially planar substrate carrying an array of sense elementsarranged to change state in response to keypad operation; and a flexiblecover disposed above the substrate and having an exposed surfacedefining an IACK interface including an array of independent key regionsarranged in rows and columns, with combination key regions betweenadjacent independent key regions, and a back surface facing thesubstrate and held away from the substrate by collapsible snap elementstherebetween, the back surface carrying an array of conductive pillslocated beneath corresponding independent key regions; wherein eachconductive pill has a contact surface facing the substrate, the contactsurface having outer regions that extend toward adjacent combination keyregions and slope away from the substrate.
 81. The IACK keypad of claim80 wherein the conductive pills are cross-shaped, with arms extendingtoward multiple adjacent combination key regions, the arms of theconductive pills comprising the sloping outer regions.
 82. The IACKkeypad of claim 80 wherein each conductive pill extends across the backsurface of the cover toward an adjacent combination key region center alateral distance equal to between about 40 percent and 99 percent of adistance between the adjacent combination key region center and a centerof the independent key region corresponding to the pill.
 83. The IACKkeypad of claim 82 wherein each conductive pill extends across the backsurface of the cover toward an adjacent combination key region center alateral distance equal to between about 50 percent and 90 percent of adistance between the adjacent combination key region center and a centerof the independent key region corresponding to the pill.
 84. The IACKkeypad of claim 83 wherein each conductive pill extends across the backsurface of the cover toward an adjacent combination key region center alateral distance equal to between about 70 percent and 80 percent of adistance between the adjacent combination key region center and a centerof the independent key region corresponding to the pill. 85-94.(canceled)